| 1. |
- Al-Jabban, Wathiq, et al.
(författare)
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A Comparative Evaluation of Cement and By-Product Petrit T in Soil Stabilization
- 2019
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Ingår i: Applied Sciences. - Switzerland : MDPI. - 2076-3417. ; 9:23
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Tidskriftsartikel (refereegranskat)abstract
- This study presents a comparison between the effectiveness of adding low binder amounts of industrial by-product Petrit T as well as cement to modify and improve fine-grained soil. Binder amount was added by soil dry weight; cement at 1%, 2%, 4% and 7% and Petrit T at 2%, 4% and 7%. The unconfined compressive strength (UCS) was used as an indicator of soil strength. In addition, the consistency limits, laser particle size analysis, and pH tests were also conducted on the treated soil. The samples were cured at 20 °C for different periods from 7 to 90 days before testing. Results indicate that cement is more effective at improving the physical and engineering properties of the treated soil. Soil plasticity index decreases after treatment and with time. Liquidity index and the water content to plastic limit ratio are introduced as new indices to define the improvement in the workability of treated soil. Soil particle size distribution is changed by reducing the clay size fraction and increasing the silt size fraction after treatment. The findings confirm that adding small binder contents improve soil properties, which subsequently reduce the environmental threats and costs that are associated with using a high amount of binder.
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| 2. |
- Al-Jabban, Wathiq, et al.
(författare)
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Briefing : Common laboratory procedures to prepare and cure stabilised soil specimens: a short review
- 2020
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Ingår i: Geotechnical Research. - UK : Institution of Civil Engineers (ICE). - 2052-6156. ; 7:1, s. 3-10
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Forskningsöversikt (refereegranskat)abstract
- Soil stabilisation is used extensively to improve the physical and mechanical properties of soils to achieve the desired strength and durability properties. During the design process, laboratory investigation is conducted firstly to obtain an enhancement in soil strength and stiffness, in addition to the type and amount of binder required. The methods of preparing and curing specimens of soil–binder mixtures directly influence the properties of the stabilised soils. The most common laboratory protocols used for preparing and curing the specimens of stabilised soil are presented in this short review. The review focuses on several aspects such as homogenisation of the natural soil, mixing type and duration, mould type, moulding techniques and curing time and condition. This review can assist various construction projects that deal with soil improvement to choose an appropriate method for preparing and curing a soil–binder mixture to simulate the field conditions as much as possible and obtain uniform soil–binder mixtures.
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| 3. |
- Al-Jabban, Wathiq, et al.
(författare)
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Effect of Disintegration Times of the Homogeneity of Soil prior to Treatment
- 2019
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Ingår i: Applied Sciences. - Switzerland : MDPI. - 2076-3417. ; 9:22
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an experimental study to investigate the effect of various disintegration times on the homogeneity of pre-treated natural soil before mixing with cementitious binders. Various disintegration times were applied, ranging from 10 s to 120 s. Four different soils were used with different characteristics from high, medium and low plasticity properties. Visual and sieving assessment were used to evaluate the best disintegration times to allow for a uniform distribution of water content and small-sized particles that would produce a uniform distribution of the binder around the soil particles. Results showed that a proper mixing time to homogenize and disintegrate the soil prior to treatment depended on several factors: soil type, water content and plasticity properties. For high plasticity soil, the disintegration time should be kept as short as possible. Increasing the disintegration time ha negative effects on the uniformity of distribution of the binder around soil particles. The homogenizing and disintegration time were less important for low plasticity soils with low water content than for medium to high plasticity soils. The findings could assist various construction projects that deal with soil improvement through preparation of soil before adding a cementitious binder to ensure uniformity of distribution of the binder around soil particles and obtain uniform soil–binder mixtures
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| 4. |
- Al-Jabban, Wathiq Jasim
(författare)
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Soil Modification by adding small amounts of binders : A laboratory study
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Soil stabilization through addition of a hydraulic binder is a method frequently used to modify and improve engineering properties of soft soils. Additives like cement and lime are typically used as stabilizers. More recently, industrial by-products, such as fly ashes, cement kiln dust, blast furnace slags and other slags have been used. The chemical reaction between the soil and the stabilizer alters the physical and engineering properties of the soil and thus desired strength and durability are obtained. The choice of appropriate type and quantity of stabilizer (binder) depends largely on factors such as soil type, moisture content, organic content, sulfate content, curing conditions (time and temperature) and the desired improvement.The objective of this thesis is to increase knowledge and understanding of how small amounts of binders change various engineering properties of stabilized soils in short- and longtime perspective. Extensive laboratory and field programs have been carried out. They cover immediate and long-term effects on the engineering properties by adding various binders. Cement, Multicem, and by-products Petrit T and Mesa were used as binders. Binder was added to the soil at various quantities: 1%, 2%, 4%, 7% and 8% of soil dry weight. The field and laboratory investigation included tests of consistency limits, sieving and hydrometer, unconfined compressive strength, density, solidification, grain size distribution using laser particle size analyzer, leaching tests and pH value. The tests were carried out on the treated soil with different binder contents and after different curing times i.e. 7, 14, 28, 60, 90 days for laboratory tests and 7 and 35 days for field investigation.The unconfined compression tests were used to show the effects of different binders on the enhancement in strength and stiffness over time. Consistency limits were determined to investigate the effects of the binders on the consistency limits, directly after treatment and over time. Laser particle size analyzer tests were conducted to investigate the effects of different binders on the particle size distribution (PSD) before and after treatment. The pH tests were conducted to investigate the effects of different binders on the alkalinity of the soil immediately after treatment and over time. This was used to give an indication of soil-binder reactions. MRM leaching tests were conducted to investigate the acidification potential of soils before and after treatment. Freeze-thaw cycles were conducted to investigate the strength characteristics after freezing and thawing in short- and long-term perspectives. Visual observation and standard dry sieving tests were conducted to optimize the proper mixing times to disintegrate or homogenize the soils by decreasing the size of agglomerated soil particles.The results show, that the variation in soil strength and stiffness of the treated soils are linked to different chemical reactions. Cement is most effective in improving the physical and engineering properties compared to the other binders studied. The plasticity index of soil decreases after treatment and over time. Liquidity index and the ratio of water content to plastic limit are introduced as new indices to illustrate the improvement in workability of treated soil by measuring the reduction in the liquidity index. This is found directly after treatment and it increases with time when the liquidity index is within the plastic range or when the water/plastic vi limit ratio is more than one. Increase of binder content and using longer curing times result in increase of soil density and decrease of water content. Particle size distribution of soil is changed by reducing the clay size fraction and increasing the silt size particles after treatment. This shows that an aggregation of particles take place resulting in coarser material than the initial. The cement-treated soils exhibit a more brittle failure in the unconfined compression tests compared to soils treated with other binder types where a more ductile behavior is observed. Applying freezing-thawing-cycles reduces the strength and stiffness of the treated soil.The appropriate length of time to homogenize and disintegrate the natural soil prior to treatment depends on several factors, such as soil type, water content, and plasticity properties of soil. For high plasticity soil, the disintegration time should be kept as short as possible. The homogenizing and disintegration time is less important for low plasticity soils with low water content than for medium to high plasticity soils.The acidification potential of soils are related to the addition of cementitious binders. The effect is found directly after treatment and over time. The treated soil exhibits higher resistance to decrease in pH value. The strength and stiffness properties found in the field investigation agree in general with those obtained from the laboratory investigation for the same binder type.
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| 5. |
- Ali, Ammar A., et al.
(författare)
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Spatial total load rating curve for a large river : A Case study of the Tigris River at Baghdad
- 2020
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Ingår i: International Journal of River Basin Management. - UK : Taylor & Francis. - 1571-5124 .- 1814-2060. ; 18:3, s. 363-376
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Tidskriftsartikel (refereegranskat)abstract
- The Tigris River in Baghdad is a large sand-bed river, supply-limited because of the implementation of a water flow regulation scheme comprising a series of reservoirs and barrages. The significant reduction in the water discharge has affected the hydraulic performance of the river and turned it into an under-fit river of complicated morphology where many islands and bank deposits have been showed up across an 18km reach in addition to the essential sinuosity. Measuring sediment load at individual cross-sections in the river gives misleading estimates and the corresponding sediment rating curve has a locally limited using. A spatially sediment rating by investigating sediment loads over the complicated reach is required to overcome the local limitations. Sediment transport rates have been investigated at 16 cross-sections along the study reach by collecting suspended load, bed load and bed material samples. Velocity profiles were measured at the sampling stations using an Acoustic Doppler Current Profiler (ADCP). The measurement results indicated that the suspended load is the dominant mode of transport (93.5%). However, bedloads were considered in determining the total loads. A spatial total load rating curve in the form of a power function was established and examined against the sediment measurements. Twenty-two previously published total load formulae where applied at the same sections and of these the Colby1964 formula gave the closest fit to the measured loads. Based on the results from this study a recommended procedure is established for using a spatial total load rating curve to estimate sediment transport rates for similar morphologically complicated rivers. Average annual transport rates during the period 2009-13 was estimated at 3.21 million tons.
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| 6. |
- Chabuk, Ali, et al.
(författare)
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Landfill Final Cover Systems Design for Arid Areas Using the HELP Model : A Case Study in the Babylon Governorate, Iraq
- 2018
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Ingår i: Sustainability. - : MDPI. - 2071-1050. ; 10:12
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Tidskriftsartikel (refereegranskat)abstract
- The main purpose of selecting proper designs for landfills is to accommodate quantities of waste without having a negative effect on the surrounding environment and human health. The Babylon Governorate (province) in Iraq was taken as an example of an arid area with very shallow groundwater and where irregular waste disposal sites had developed that had not been subject to international standards when they were selected for landfill use. In the current study, the suggested design for landfills is a base liner and final cover system. In this suggested design, the final cover system allows for three scenarios. The first scenario considers an evapotranspiration soil cover (ET) (capillary barriers type), the second scenario is a modified cover design of “RCRA Subtitle D”, and the third scenario is a combination of the first and second scenarios. The HELP 3.95 D model was applied to the selected landfill sites in the governorate to check if there was any penetration of the leachate that might in future percolate from the landfill’s bottom barrier layer in arid areas. The results from the suggested landfill design showed that there was no leachate percolation from the bottom barrier layer using the second and third scenarios. For the first scenario, however, there was a small amount of leachate through the bottom barrier layer in the years 2013 and 2014.
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| 7. |
- Abdullah, Twana, et al.
(författare)
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Assessment of groundwater vulnerability to pollution using two different vulnerability models in Halabja-Saidsadiq Basin, Iraq
- 2020
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Ingår i: Groundwater for Sustainable Development. - : Elsevier. - 2352-801X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Groundwater aquifer in Halabja-Saidsadiq Basin considered as one of the most important aquifers in terms of water supplying in Kurdistan Region, NE of Iraq. The growing of economics, irrigation and agricultural activities inside the basin makes it of the main essentials to the region. Therefore, pollution of groundwater is of specific worry as groundwater resources are the principal source of water for drinking, agriculture, irrigation and industrial activities. Thus, the best and practical arrangement is to keep the pollution of groundwater through. The current study aims to evaluate of the vulnerability of groundwater aquifers of the study area. Two models were applied, to be specific VLDA and COP to develop maps of groundwater vulnerability for contamination. The VLDA model classified the area into four classes of vulnerability: low, moderate, high and very high with coverage area of (2%,44%,53% and 1%), respectively. While four vulnerability classes were accomplished dependent on COP model including very low, low, moderate and high vulnerability classes with coverage areas of (1%, 37%, 2% and 60%) respectively. To confirm the suitability of each map for assessment of groundwater vulnerability in the area, it required to be validated of the theoretical sympathetic of current hydrogeological conditions. In this study, groundwater age evaluated utilizing tritium isotopes investigation and applied it to validate the vulnerability results. Based on this validation, the outcome exhibits that the vulnerability classes acquired utilizing VLDA model are more predictable contrasted with the COP model.
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| 8. |
- Abdullah, Twana, 1977-
(författare)
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Groundwater Vulnerability Assessment to pollution in Different Soil and Rock Materials
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The augmentation of human population regularly corresponds with change in the land cover, including expansion of urban areas, which imposes increasing the available amount of domestic and drinking water. The study area, Halabja-Saidsadiq Basin, is situated in the Northeast of Iraq and is one of the major groundwater sources of the region. As the surface water sources are not enough in the studied area, it has become necessary to use groundwater at an increasing rate. Usually, a huge amount of groundwater is plentiful in the alluvial deposits or rock outcrops where the urban areas are frequently situated. Such areas face a huge risk of pollution of groundwater due to producing different sources of a contaminant from human's activity. Keeping these aspects in view, groundwater vulnerability studies have been carried out in the current studied basin. The main objective of this work is to investigate the environmental impacts on groundwater quality and recognize the groundwater vulnerability in the area so that the groundwater can be protected from probable contaminations.In the current study, DRASTIC model has been applied since it is one of the most proper useful methods available for the assessment of the groundwater vulnerability. This model has been modified in different ways to achieve the obvious vulnerability condition in the area; likewise, different further methods have been applied for comparison purposes such as: weight modified VLDA and standard COP models. In addition, the applied models were validated by comparing its findings against the estimated groundwater ages and the observed water characteristic qualities within the region in two successive seasons.According to the spatial distribution of irrigation water quality index, groundwater at the studied basin classified into three group for both dry and wet seasons, namely, Sever Restriction (SR), High Restriction (HR) and Moderate Restriction (MR). The coverage area of all three classes are (1.4%, 52.4% and46.2%) for dry season and (0.7%, 83.3% and16%) for wet seasons, respectively. While, refer to the water quality index for drinking purpose, groundwater in this basin reveals a permissible to excellent groundwater quality of the dry season and a good to excellent groundwater quality of the wet season. The high level of a good groundwater quality in the wet season compared to the dry season might be expected to the groundwater recharge during the winter and spring periods, which lead to dilution of chemical component, in contrast high irrigation and agricultural activities and groundwater discharge in the dry season leads to increase the concentration of chemical component.Field and official data were collected to review several environmental impacts and were used to map standard DRASTIC vulnerability model for the study basin. Based on this model, the study area was classified into four zones of vulnerability indexes, comprises a very low, low, moderate and high vulnerability index with a coverage area of (34%, 13%, 48% and 5%) respectively.In the first modification step, the rate and weight value of each parameter in DRASTIC model is modified. Nitrate concentration from 39 groundwater samples was used for modifying the recommended standard rating value based on the Wilcoxon rank-sum nonparametric statistical test and then sensitivity analysis was used to modifying recommended standard weighting value of each parameter. To calibrate the modified rate, the Pearson's correlation coefficient was applied to estimate the relation between DRASTIC values and nitrate concentrations in groundwater samples. For the first modified model, the correlation coefficient was 72% that was significantly higher than 43% achieved for the standard model. The modified model classified the area into five vulnerability classes, including (very low, low, moderate, high and very high) with covered area of (7%, 35%, 19%, 35% and 4%), respectively.The second modification of DRASTIC model was based on land use and land cover for the studied area. The land use and land cover (LULC) map prepared using ERDAS IMAGINE software from two different scenes of Landsat Thematic Mapper (TM). The LULC map indicates that only five classes of LULC can be identified: these are: barren land, agricultural land, vegetation land, urban area and wet land or water body. The modified DRASTIC based on LULC map classified the area into five classes with different coverage area of each class: very low (1.17%), low (36.82%), moderate (17.57%), high (43.42%) and very high (1.02%).The third modified method of the current study is the modification of DRASTIC model based on Lineament feature of the study basin. A lineament map is extracted from Enhanced Thematic Mapper plus (ETM+) satellite imagery using different techniques in remote sensing and GIS. The lineament density map demonstrates that only six classes of lineament density can be identified ranged from (0-2.4). The third modified DRASTIC model classified the area into four vulnerability categories: very low (28.75%), low (14.31%), moderate (46.91%) and high (10.03%).The fourth effort to modify standard DRASTIC model is the application of Analytical Hierarchical Process (AHP) to assess the weight value of each parameter. The modified DRASTIC vulnerability index values based on AHP method ranged between (65.82–224.1) with five vulnerability classes comprises (very low to very high).Weight modified VLDA and standard COP models were also applied to map vulnerability system in the study basin. The vulnerability outcome based on weight modified VLDA model revealed that a total of four ranges of vulnerability indexes had been distinguished ranging from low to very high with vulnerability indexes (2.133-9.16). Subsequently, based on the standard COP model, the area is also divided into four vulnerability classes ranging from very low to high with index value ranged from (0.79) to (6.2).All applied models in the study basin were compared to each other and validated to clarify the validity of the theoretical sympathetic of current hydrogeological conditions and to show the accuracy of the modeled vulnerability system. Two methods were applied for the validation of the result, in the first approach; nitrate concentration analysis has been selected; the nitrate differences between two following seasons (dry and wet) were analyzed from (39) water wells. In the second approach, groundwater vulnerability was assessed based on estimated groundwater age from range of tritium (3H) value in the groundwater samples from different groundwater aquifers in the studied area. The results of both validation methods verify the sensibility of the gradation and distribution of vulnerability levels acquired using the modified DRASTIC model based on (rate and weight modification, weight modification based on AHP process and effect of LULC on DRASTIC model) and also applying weight modified of VLDA model.
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| 9. |
- Abdullah, Twana, et al.
(författare)
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Hydrogeochemical Evaluation of Groundwater and Its Suitability for Domestic Uses in Halabja Saidsadiq Basin, Iraq
- 2019
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Ingår i: Water. - Switzerland : MDPI. - 2073-4441. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- Evaluation of the hydrogeochemical characteristics and groundwater suitability for domestic use was conducted in the Halabja Saidsadiq Basin in the northeastern part of Iraq. The total studied area is about 1278 km 2 with a specific Mediterranean-type continental interior climate, which is cold in winter and hot in summer. To conduct the required laboratory chemical analysis for groundwater samples in the studied basin, 78 groundwater samples, in total, were collected from 39 water wells in the dry and wet seasons in 2014 and analyzed for major cations and anions, and the results were compared with the permitted limits for drinking water. An examination of the chemical concentrations of the World Health Organization drinking water norms demonstrate that a large portion of the groundwater samples is suitable for drinking, and a preponderance of groundwater samples situated in the class of hard and very hard water types for both seasons. Suitability of groundwater for drinking use was additionally assessed according to the water quality index classification. This showed that more than 98% of groundwater samples have good water quality in the dry and wet seasons. Conversely, the classification of groundwater samples based on Piper’s diagram designates that the groundwater type is alkaline water, with existing bicarbonate along with sulfate and chloride. However, water–ock exchange processes and groundwater flow have been responsible for the dominant water type of Ca–g–CO3.
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| 10. |
- Abdullah, Twana O., et al.
(författare)
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Magnitude and Direction of Groundwater Seepage Velocity in Different Soil and Rock Materials
- 2020
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Ingår i: Engineering. - USA : Scientific Research Publishing. - 1947-3931 .- 1947-394X. ; 12:4, s. 242-253
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Tidskriftsartikel (refereegranskat)abstract
- To understand and anticipate flow in various groundwater media, the magnitude and direction of groundwater flow velocity must be deemed. The studied area which is called Halabja-Sadiq Basin is in the northeastern part of Iraq and covers an area of approximately 128,000 square hectometers. There are several groundwater aquifers in this region that supply nearly over 90% of all water needs. Subsequently, it is of highly requirement to identify various groundwater behaviors in the area. The objective of this study is to estimate the magnitude and direction of the groundwater seepage velocity with the aid of groundwater tool in Geographic Information System technology. Refer to the results of this analysis, the magnitude value of groundwater flow velocity ranged from 0 to 51 m/d, whilst the general flow movement is from the eastern part to the western part of the study area. The factor governing the direction of flow and velocity magnitude indicates the direction of dipping of the geological formation strata, the high head of groundwater in the eastern part, and the low transmissivity properties of aquifer materials in the western part.
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